text: import {FETCH_POSTS, FETCH_POST, DELETE_POST} from '../actions';
  import _ from 'lodash';
  
  export default function(state = {}, action) {
    switch(action.type) {
      case FETCH_POSTS:
        return _.mapKeys(action.payload.data, 'id');
      case FETCH_POST:
        const post = action.payload.data;
  
        // ES5
        // const newState = {...state };
        // newState[post.id] = post;
        // return newState;
  
        return {...state, [action.payload.data.id]: action.payload.data};
      case DELETE_POST:
        return _.omit(state, action.payload);
      default: 
        return state;
    }
  }